/* -*- Mode: C; indent-tabs-mode:t ; c-basic-offset:8 -*- */
/*
 * USB descriptor handling functions for libusb
 * Copyright © 2007 Daniel Drake <dsd@gentoo.org>
 * Copyright © 2001 Johannes Erdfelt <johannes@erdfelt.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <errno.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>

#include "libusbi.h"

#define DESC_HEADER_LENGTH        2
#define DEVICE_DESC_LENGTH        18
#define CONFIG_DESC_LENGTH        9
#define INTERFACE_DESC_LENGTH        9
#define ENDPOINT_DESC_LENGTH        7
#define ENDPOINT_AUDIO_DESC_LENGTH    9

/** @defgroup desc USB descriptors
 * This page details how to examine the various standard USB descriptors
 * for detected devices
 */

/* set host_endian if the w values are already in host endian format,
 * as opposed to bus endian. */
int usbi_parse_descriptor(const unsigned char *source, const char *descriptor,
    void *dest, int host_endian)
{
    const unsigned char *sp = source;
    unsigned char *dp = dest;
    uint16_t w;
    const char *cp;
    uint32_t d;

    for (cp = descriptor; *cp; cp++) {
        switch (*cp) {
            case 'b':    /* 8-bit byte */
                *dp++ = *sp++;
                break;
            case 'w':    /* 16-bit word, convert from little endian to CPU */
                dp += ((uintptr_t)dp & 1);    /* Align to word boundary */

                if (host_endian) {
                    memcpy(dp, sp, 2);
                } else {
                    w = (sp[1] << 8) | sp[0];
                    *((uint16_t *)dp) = w;
                }
                sp += 2;
                dp += 2;
                break;
            case 'd':    /* 32-bit word, convert from little endian to CPU */
                dp += ((uintptr_t)dp & 1);    /* Align to word boundary */

                if (host_endian) {
                    memcpy(dp, sp, 4);
                } else {
                    d = (sp[3] << 24) | (sp[2] << 16) |
                        (sp[1] << 8) | sp[0];
                    *((uint32_t *)dp) = d;
                }
                sp += 4;
                dp += 4;
                break;
            case 'u':    /* 16 byte UUID */
                memcpy(dp, sp, 16);
                sp += 16;
                dp += 16;
                break;
        }
    }

    return (int) (sp - source);
}

static void clear_endpoint(struct libusb_endpoint_descriptor *endpoint)
{
    if (endpoint->extra)
        free((unsigned char *) endpoint->extra);
}

static int parse_endpoint(struct libusb_context *ctx,
    struct libusb_endpoint_descriptor *endpoint, unsigned char *buffer,
    int size, int host_endian)
{
    struct usb_descriptor_header header;
    unsigned char *extra;
    unsigned char *begin;
    int parsed = 0;
    int len;

    if (size < DESC_HEADER_LENGTH) {
        usbi_err(ctx, "short endpoint descriptor read %d/%d",
             size, DESC_HEADER_LENGTH);
        return LIBUSB_ERROR_IO;
    }

    usbi_parse_descriptor(buffer, "bb", &header, 0);
    if (header.bDescriptorType != LIBUSB_DT_ENDPOINT) {
        usbi_err(ctx, "unexpected descriptor %x (expected %x)",
            header.bDescriptorType, LIBUSB_DT_ENDPOINT);
        return parsed;
    }
    if (header.bLength > size) {
        usbi_warn(ctx, "short endpoint descriptor read %d/%d",
              size, header.bLength);
        return parsed;
    }
    if (header.bLength >= ENDPOINT_AUDIO_DESC_LENGTH)
        usbi_parse_descriptor(buffer, "bbbbwbbb", endpoint, host_endian);
    else if (header.bLength >= ENDPOINT_DESC_LENGTH)
        usbi_parse_descriptor(buffer, "bbbbwb", endpoint, host_endian);
    else {
        usbi_err(ctx, "invalid endpoint bLength (%d)", header.bLength);
        return LIBUSB_ERROR_IO;
    }

    buffer += header.bLength;
    size -= header.bLength;
    parsed += header.bLength;

    /* Skip over the rest of the Class Specific or Vendor Specific */
    /*  descriptors */
    begin = buffer;
    while (size >= DESC_HEADER_LENGTH) {
        usbi_parse_descriptor(buffer, "bb", &header, 0);
        if (header.bLength < DESC_HEADER_LENGTH) {
            usbi_err(ctx, "invalid extra ep desc len (%d)",
                 header.bLength);
            return LIBUSB_ERROR_IO;
        } else if (header.bLength > size) {
            usbi_warn(ctx, "short extra ep desc read %d/%d",
                  size, header.bLength);
            return parsed;
        }

        /* If we find another "proper" descriptor then we're done  */
        if ((header.bDescriptorType == LIBUSB_DT_ENDPOINT) ||
                (header.bDescriptorType == LIBUSB_DT_INTERFACE) ||
                (header.bDescriptorType == LIBUSB_DT_CONFIG) ||
                (header.bDescriptorType == LIBUSB_DT_DEVICE))
            break;

        usbi_dbg("skipping descriptor %x", header.bDescriptorType);
        buffer += header.bLength;
        size -= header.bLength;
        parsed += header.bLength;
    }

    /* Copy any unknown descriptors into a storage area for drivers */
    /*  to later parse */
    len = (int)(buffer - begin);
    if (!len) {
        endpoint->extra = NULL;
        endpoint->extra_length = 0;
        return parsed;
    }

    extra = malloc(len);
    endpoint->extra = extra;
    if (!extra) {
        endpoint->extra_length = 0;
        return LIBUSB_ERROR_NO_MEM;
    }

    memcpy(extra, begin, len);
    endpoint->extra_length = len;

    return parsed;
}

static void clear_interface(struct libusb_interface *usb_interface)
{
    int i;
    int j;

    if (usb_interface->altsetting) {
        for (i = 0; i < usb_interface->num_altsetting; i++) {
            struct libusb_interface_descriptor *ifp =
                (struct libusb_interface_descriptor *)
                usb_interface->altsetting + i;
            if (ifp->extra)
                free((void *) ifp->extra);
            if (ifp->endpoint) {
                for (j = 0; j < ifp->bNumEndpoints; j++)
                    clear_endpoint((struct libusb_endpoint_descriptor *)
                        ifp->endpoint + j);
                free((void *) ifp->endpoint);
            }
        }
        free((void *) usb_interface->altsetting);
        usb_interface->altsetting = NULL;
    }

}

static int parse_interface(libusb_context *ctx,
    struct libusb_interface *usb_interface, unsigned char *buffer, int size,
    int host_endian)
{
    int i;
    int len;
    int r;
    int parsed = 0;
    int interface_number = -1;
    size_t tmp;
    struct usb_descriptor_header header;
    struct libusb_interface_descriptor *ifp;
    unsigned char *begin;

    usb_interface->num_altsetting = 0;

    while (size >= INTERFACE_DESC_LENGTH) {
        struct libusb_interface_descriptor *altsetting =
            (struct libusb_interface_descriptor *) usb_interface->altsetting;
        altsetting = usbi_reallocf(altsetting,
            sizeof(struct libusb_interface_descriptor) *
            (usb_interface->num_altsetting + 1));
        if (!altsetting) {
            r = LIBUSB_ERROR_NO_MEM;
            goto err;
        }
        usb_interface->altsetting = altsetting;

        ifp = altsetting + usb_interface->num_altsetting;
        usbi_parse_descriptor(buffer, "bbbbbbbbb", ifp, 0);
        if (ifp->bDescriptorType != LIBUSB_DT_INTERFACE) {
            usbi_err(ctx, "unexpected descriptor %x (expected %x)",
                 ifp->bDescriptorType, LIBUSB_DT_INTERFACE);
            return parsed;
        }
        if (ifp->bLength < INTERFACE_DESC_LENGTH) {
            usbi_err(ctx, "invalid interface bLength (%d)",
                 ifp->bLength);
            r = LIBUSB_ERROR_IO;
            goto err;
        }
        if (ifp->bLength > size) {
            usbi_warn(ctx, "short intf descriptor read %d/%d",
                 size, ifp->bLength);
            return parsed;
        }
        if (ifp->bNumEndpoints > USB_MAXENDPOINTS) {
            usbi_err(ctx, "too many endpoints (%d)", ifp->bNumEndpoints);
            r = LIBUSB_ERROR_IO;
            goto err;
        }

        usb_interface->num_altsetting++;
        ifp->extra = NULL;
        ifp->extra_length = 0;
        ifp->endpoint = NULL;

        if (interface_number == -1)
            interface_number = ifp->bInterfaceNumber;

        /* Skip over the interface */
        buffer += ifp->bLength;
        parsed += ifp->bLength;
        size -= ifp->bLength;

        begin = buffer;

        /* Skip over any interface, class or vendor descriptors */
        while (size >= DESC_HEADER_LENGTH) {
            usbi_parse_descriptor(buffer, "bb", &header, 0);
            if (header.bLength < DESC_HEADER_LENGTH) {
                usbi_err(ctx,
                     "invalid extra intf desc len (%d)",
                     header.bLength);
                r = LIBUSB_ERROR_IO;
                goto err;
            } else if (header.bLength > size) {
                usbi_warn(ctx,
                      "short extra intf desc read %d/%d",
                      size, header.bLength);
                return parsed;
            }

            /* If we find another "proper" descriptor then we're done */
            if ((header.bDescriptorType == LIBUSB_DT_INTERFACE) ||
                    (header.bDescriptorType == LIBUSB_DT_ENDPOINT) ||
                    (header.bDescriptorType == LIBUSB_DT_CONFIG) ||
                    (header.bDescriptorType == LIBUSB_DT_DEVICE))
                break;

            buffer += header.bLength;
            parsed += header.bLength;
            size -= header.bLength;
        }

        /* Copy any unknown descriptors into a storage area for */
        /*  drivers to later parse */
        len = (int)(buffer - begin);
        if (len) {
            ifp->extra = malloc(len);
            if (!ifp->extra) {
                r = LIBUSB_ERROR_NO_MEM;
                goto err;
            }
            memcpy((unsigned char *) ifp->extra, begin, len);
            ifp->extra_length = len;
        }

        if (ifp->bNumEndpoints > 0) {
            struct libusb_endpoint_descriptor *endpoint;
            tmp = ifp->bNumEndpoints * sizeof(struct libusb_endpoint_descriptor);
            endpoint = malloc(tmp);
            ifp->endpoint = endpoint;
            if (!endpoint) {
                r = LIBUSB_ERROR_NO_MEM;
                goto err;
            }

            memset(endpoint, 0, tmp);
            for (i = 0; i < ifp->bNumEndpoints; i++) {
                r = parse_endpoint(ctx, endpoint + i, buffer, size,
                    host_endian);
                if (r < 0)
                    goto err;
                if (r == 0) {
                    ifp->bNumEndpoints = (uint8_t)i;
                    break;;
                }

                buffer += r;
                parsed += r;
                size -= r;
            }
        }

        /* We check to see if it's an alternate to this one */
        ifp = (struct libusb_interface_descriptor *) buffer;
        if (size < LIBUSB_DT_INTERFACE_SIZE ||
                ifp->bDescriptorType != LIBUSB_DT_INTERFACE ||
                ifp->bInterfaceNumber != interface_number)
            return parsed;
    }

    return parsed;
err:
    clear_interface(usb_interface);
    return r;
}

static void clear_configuration(struct libusb_config_descriptor *config)
{
    if (config->interface) {
        int i;
        for (i = 0; i < config->bNumInterfaces; i++)
            clear_interface((struct libusb_interface *)
                config->interface + i);
        free((void *) config->interface);
    }
    if (config->extra)
        free((void *) config->extra);
}

static int parse_configuration(struct libusb_context *ctx,
    struct libusb_config_descriptor *config, unsigned char *buffer,
    int size, int host_endian)
{
    int i;
    int r;
    size_t tmp;
    struct usb_descriptor_header header;
    struct libusb_interface *usb_interface;

    if (size < LIBUSB_DT_CONFIG_SIZE) {
        usbi_err(ctx, "short config descriptor read %d/%d",
             size, LIBUSB_DT_CONFIG_SIZE);
        return LIBUSB_ERROR_IO;
    }

    usbi_parse_descriptor(buffer, "bbwbbbbb", config, host_endian);
    if (config->bDescriptorType != LIBUSB_DT_CONFIG) {
        usbi_err(ctx, "unexpected descriptor %x (expected %x)",
             config->bDescriptorType, LIBUSB_DT_CONFIG);
        return LIBUSB_ERROR_IO;
    }
    if (config->bLength < LIBUSB_DT_CONFIG_SIZE) {
        usbi_err(ctx, "invalid config bLength (%d)", config->bLength);
        return LIBUSB_ERROR_IO;
    }
    if (config->bLength > size) {
        usbi_err(ctx, "short config descriptor read %d/%d",
             size, config->bLength);
        return LIBUSB_ERROR_IO;
    }
    if (config->bNumInterfaces > USB_MAXINTERFACES) {
        usbi_err(ctx, "too many interfaces (%d)", config->bNumInterfaces);
        return LIBUSB_ERROR_IO;
    }

    tmp = config->bNumInterfaces * sizeof(struct libusb_interface);
    usb_interface = malloc(tmp);
    config->interface = usb_interface;
    if (!config->interface)
        return LIBUSB_ERROR_NO_MEM;

    memset(usb_interface, 0, tmp);
    buffer += config->bLength;
    size -= config->bLength;

    config->extra = NULL;
    config->extra_length = 0;

    for (i = 0; i < config->bNumInterfaces; i++) {
        int len;
        unsigned char *begin;

        /* Skip over the rest of the Class Specific or Vendor */
        /*  Specific descriptors */
        begin = buffer;
        while (size >= DESC_HEADER_LENGTH) {
            usbi_parse_descriptor(buffer, "bb", &header, 0);

            if (header.bLength < DESC_HEADER_LENGTH) {
                usbi_err(ctx,
                     "invalid extra config desc len (%d)",
                     header.bLength);
                r = LIBUSB_ERROR_IO;
                goto err;
            } else if (header.bLength > size) {
                usbi_warn(ctx,
                      "short extra config desc read %d/%d",
                      size, header.bLength);
                config->bNumInterfaces = (uint8_t)i;
                return size;
            }

            /* If we find another "proper" descriptor then we're done */
            if ((header.bDescriptorType == LIBUSB_DT_ENDPOINT) ||
                    (header.bDescriptorType == LIBUSB_DT_INTERFACE) ||
                    (header.bDescriptorType == LIBUSB_DT_CONFIG) ||
                    (header.bDescriptorType == LIBUSB_DT_DEVICE))
                break;

            usbi_dbg("skipping descriptor 0x%x\n", header.bDescriptorType);
            buffer += header.bLength;
            size -= header.bLength;
        }

        /* Copy any unknown descriptors into a storage area for */
        /*  drivers to later parse */
        len = (int)(buffer - begin);
        if (len) {
            /* FIXME: We should realloc and append here */
            if (!config->extra_length) {
                config->extra = malloc(len);
                if (!config->extra) {
                    r = LIBUSB_ERROR_NO_MEM;
                    goto err;
                }

                memcpy((unsigned char *) config->extra, begin, len);
                config->extra_length = len;
            }
        }

        r = parse_interface(ctx, usb_interface + i, buffer, size, host_endian);
        if (r < 0)
            goto err;
        if (r == 0) {
            config->bNumInterfaces = (uint8_t)i;
            break;
        }

        buffer += r;
        size -= r;
    }

    return size;

err:
    clear_configuration(config);
    return r;
}

static int raw_desc_to_config(struct libusb_context *ctx,
    unsigned char *buf, int size, int host_endian,
    struct libusb_config_descriptor **config)
{
    struct libusb_config_descriptor *_config = malloc(sizeof(*_config));
    int r;

    if (!_config)
        return LIBUSB_ERROR_NO_MEM;

    r = parse_configuration(ctx, _config, buf, size, host_endian);
    if (r < 0) {
        usbi_err(ctx, "parse_configuration failed with error %d", r);
        free(_config);
        return r;
    } else if (r > 0) {
        usbi_warn(ctx, "still %d bytes of descriptor data left", r);
    }

    *config = _config;
    return LIBUSB_SUCCESS;
}

int usbi_device_cache_descriptor(libusb_device *dev)
{
    int r, host_endian = 0;

    r = usbi_backend->get_device_descriptor(dev, (unsigned char *) &dev->device_descriptor,
                        &host_endian);
    if (r < 0)
        return r;

    if (!host_endian) {
        dev->device_descriptor.bcdUSB = libusb_le16_to_cpu(dev->device_descriptor.bcdUSB);
        dev->device_descriptor.idVendor = libusb_le16_to_cpu(dev->device_descriptor.idVendor);
        dev->device_descriptor.idProduct = libusb_le16_to_cpu(dev->device_descriptor.idProduct);
        dev->device_descriptor.bcdDevice = libusb_le16_to_cpu(dev->device_descriptor.bcdDevice);
    }

    return LIBUSB_SUCCESS;
}

/** \ingroup desc
 * Get the USB device descriptor for a given device.
 *
 * This is a non-blocking function; the device descriptor is cached in memory.
 *
 * Note since libusb-1.0.16, \ref LIBUSB_API_VERSION >= 0x01000102, this
 * function always succeeds.
 *
 * \param dev the device
 * \param desc output location for the descriptor data
 * \returns 0 on success or a LIBUSB_ERROR code on failure
 */
int API_EXPORTED libusb_get_device_descriptor(libusb_device *dev,
    struct libusb_device_descriptor *desc)
{
    usbi_dbg("");
    memcpy((unsigned char *) desc, (unsigned char *) &dev->device_descriptor,
           sizeof (dev->device_descriptor));
    return 0;
}

/** \ingroup desc
 * Get the USB configuration descriptor for the currently active configuration.
 * This is a non-blocking function which does not involve any requests being
 * sent to the device.
 *
 * \param dev a device
 * \param config output location for the USB configuration descriptor. Only
 * valid if 0 was returned. Must be freed with libusb_free_config_descriptor()
 * after use.
 * \returns 0 on success
 * \returns LIBUSB_ERROR_NOT_FOUND if the device is in unconfigured state
 * \returns another LIBUSB_ERROR code on error
 * \see libusb_get_config_descriptor
 */
int API_EXPORTED libusb_get_active_config_descriptor(libusb_device *dev,
    struct libusb_config_descriptor **config)
{
    struct libusb_config_descriptor _config;
    unsigned char tmp[LIBUSB_DT_CONFIG_SIZE];
    unsigned char *buf = NULL;
    int host_endian = 0;
    int r;

    r = usbi_backend->get_active_config_descriptor(dev, tmp,
        LIBUSB_DT_CONFIG_SIZE, &host_endian);
    if (r < 0)
        return r;
    if (r < LIBUSB_DT_CONFIG_SIZE) {
        usbi_err(dev->ctx, "short config descriptor read %d/%d",
             r, LIBUSB_DT_CONFIG_SIZE);
        return LIBUSB_ERROR_IO;
    }

    usbi_parse_descriptor(tmp, "bbw", &_config, host_endian);
    buf = malloc(_config.wTotalLength);
    if (!buf)
        return LIBUSB_ERROR_NO_MEM;

    r = usbi_backend->get_active_config_descriptor(dev, buf,
        _config.wTotalLength, &host_endian);
    if (r >= 0)
        r = raw_desc_to_config(dev->ctx, buf, r, host_endian, config);

    free(buf);
    return r;
}

/** \ingroup desc
 * Get a USB configuration descriptor based on its index.
 * This is a non-blocking function which does not involve any requests being
 * sent to the device.
 *
 * \param dev a device
 * \param config_index the index of the configuration you wish to retrieve
 * \param config output location for the USB configuration descriptor. Only
 * valid if 0 was returned. Must be freed with libusb_free_config_descriptor()
 * after use.
 * \returns 0 on success
 * \returns LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
 * \returns another LIBUSB_ERROR code on error
 * \see libusb_get_active_config_descriptor()
 * \see libusb_get_config_descriptor_by_value()
 */
int API_EXPORTED libusb_get_config_descriptor(libusb_device *dev,
    uint8_t config_index, struct libusb_config_descriptor **config)
{
    struct libusb_config_descriptor _config;
    unsigned char tmp[LIBUSB_DT_CONFIG_SIZE];
    unsigned char *buf = NULL;
    int host_endian = 0;
    int r;

    usbi_dbg("index %d", config_index);
    if (config_index >= dev->num_configurations)
        return LIBUSB_ERROR_NOT_FOUND;

    r = usbi_backend->get_config_descriptor(dev, config_index, tmp,
        LIBUSB_DT_CONFIG_SIZE, &host_endian);
    if (r < 0)
        return r;
    if (r < LIBUSB_DT_CONFIG_SIZE) {
        usbi_err(dev->ctx, "short config descriptor read %d/%d",
             r, LIBUSB_DT_CONFIG_SIZE);
        return LIBUSB_ERROR_IO;
    }

    usbi_parse_descriptor(tmp, "bbw", &_config, host_endian);
    buf = malloc(_config.wTotalLength);
    if (!buf)
        return LIBUSB_ERROR_NO_MEM;

    r = usbi_backend->get_config_descriptor(dev, config_index, buf,
        _config.wTotalLength, &host_endian);
    if (r >= 0)
        r = raw_desc_to_config(dev->ctx, buf, r, host_endian, config);

    free(buf);
    return r;
}

/* iterate through all configurations, returning the index of the configuration
 * matching a specific bConfigurationValue in the idx output parameter, or -1
 * if the config was not found.
 * returns 0 on success or a LIBUSB_ERROR code
 */
int usbi_get_config_index_by_value(struct libusb_device *dev,
    uint8_t bConfigurationValue, int *idx)
{
    uint8_t i;

    usbi_dbg("value %d", bConfigurationValue);
    for (i = 0; i < dev->num_configurations; i++) {
        unsigned char tmp[6];
        int host_endian;
        int r = usbi_backend->get_config_descriptor(dev, i, tmp, sizeof(tmp),
            &host_endian);
        if (r < 0) {
            *idx = -1;
            return r;
        }
        if (tmp[5] == bConfigurationValue) {
            *idx = i;
            return 0;
        }
    }

    *idx = -1;
    return 0;
}

/** \ingroup desc
 * Get a USB configuration descriptor with a specific bConfigurationValue.
 * This is a non-blocking function which does not involve any requests being
 * sent to the device.
 *
 * \param dev a device
 * \param bConfigurationValue the bConfigurationValue of the configuration you
 * wish to retrieve
 * \param config output location for the USB configuration descriptor. Only
 * valid if 0 was returned. Must be freed with libusb_free_config_descriptor()
 * after use.
 * \returns 0 on success
 * \returns LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
 * \returns another LIBUSB_ERROR code on error
 * \see libusb_get_active_config_descriptor()
 * \see libusb_get_config_descriptor()
 */
int API_EXPORTED libusb_get_config_descriptor_by_value(libusb_device *dev,
    uint8_t bConfigurationValue, struct libusb_config_descriptor **config)
{
    int r, idx, host_endian;
    unsigned char *buf = NULL;

    if (usbi_backend->get_config_descriptor_by_value) {
        r = usbi_backend->get_config_descriptor_by_value(dev,
            bConfigurationValue, &buf, &host_endian);
        if (r < 0)
            return r;
        return raw_desc_to_config(dev->ctx, buf, r, host_endian, config);
    }

    r = usbi_get_config_index_by_value(dev, bConfigurationValue, &idx);
    if (r < 0)
        return r;
    else if (idx == -1)
        return LIBUSB_ERROR_NOT_FOUND;
    else
        return libusb_get_config_descriptor(dev, (uint8_t) idx, config);
}

/** \ingroup desc
 * Free a configuration descriptor obtained from
 * libusb_get_active_config_descriptor() or libusb_get_config_descriptor().
 * It is safe to call this function with a NULL config parameter, in which
 * case the function simply returns.
 *
 * \param config the configuration descriptor to free
 */
void API_EXPORTED libusb_free_config_descriptor(
    struct libusb_config_descriptor *config)
{
    if (!config)
        return;

    clear_configuration(config);
    free(config);
}

/** \ingroup desc
 * Get an endpoints superspeed endpoint companion descriptor (if any)
 *
 * \param ctx the context to operate on, or NULL for the default context
 * \param endpoint endpoint descriptor from which to get the superspeed
 * endpoint companion descriptor
 * \param ep_comp output location for the superspeed endpoint companion
 * descriptor. Only valid if 0 was returned. Must be freed with
 * libusb_free_ss_endpoint_companion_descriptor() after use.
 * \returns 0 on success
 * \returns LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
 * \returns another LIBUSB_ERROR code on error
 */
int API_EXPORTED libusb_get_ss_endpoint_companion_descriptor(
    struct libusb_context *ctx,
    const struct libusb_endpoint_descriptor *endpoint,
    struct libusb_ss_endpoint_companion_descriptor **ep_comp)
{
    struct usb_descriptor_header header;
    int size = endpoint->extra_length;
    const unsigned char *buffer = endpoint->extra;

    *ep_comp = NULL;

    while (size >= DESC_HEADER_LENGTH) {
        usbi_parse_descriptor(buffer, "bb", &header, 0);
        if (header.bLength < 2 || header.bLength > size) {
            usbi_err(ctx, "invalid descriptor length %d",
                 header.bLength);
            return LIBUSB_ERROR_IO;
        }
        if (header.bDescriptorType != LIBUSB_DT_SS_ENDPOINT_COMPANION) {
            buffer += header.bLength;
            size -= header.bLength;
            continue;
        }
        if (header.bLength < LIBUSB_DT_SS_ENDPOINT_COMPANION_SIZE) {
            usbi_err(ctx, "invalid ss-ep-comp-desc length %d",
                 header.bLength);
            return LIBUSB_ERROR_IO;
        }
        *ep_comp = malloc(sizeof(**ep_comp));
        if (*ep_comp == NULL)
            return LIBUSB_ERROR_NO_MEM;
        usbi_parse_descriptor(buffer, "bbbbw", *ep_comp, 0);
        return LIBUSB_SUCCESS;
    }
    return LIBUSB_ERROR_NOT_FOUND;
}

/** \ingroup desc
 * Free a superspeed endpoint companion descriptor obtained from
 * libusb_get_ss_endpoint_companion_descriptor().
 * It is safe to call this function with a NULL ep_comp parameter, in which
 * case the function simply returns.
 *
 * \param ep_comp the superspeed endpoint companion descriptor to free
 */
void API_EXPORTED libusb_free_ss_endpoint_companion_descriptor(
    struct libusb_ss_endpoint_companion_descriptor *ep_comp)
{
    free(ep_comp);
}

static int parse_bos(struct libusb_context *ctx,
    struct libusb_bos_descriptor **bos,
    unsigned char *buffer, int size, int host_endian)
{
    struct libusb_bos_descriptor bos_header, *_bos;
    struct libusb_bos_dev_capability_descriptor dev_cap;
    int i;

    if (size < LIBUSB_DT_BOS_SIZE) {
        usbi_err(ctx, "short bos descriptor read %d/%d",
             size, LIBUSB_DT_BOS_SIZE);
        return LIBUSB_ERROR_IO;
    }

    usbi_parse_descriptor(buffer, "bbwb", &bos_header, host_endian);
    if (bos_header.bDescriptorType != LIBUSB_DT_BOS) {
        usbi_err(ctx, "unexpected descriptor %x (expected %x)",
             bos_header.bDescriptorType, LIBUSB_DT_BOS);
        return LIBUSB_ERROR_IO;
    }
    if (bos_header.bLength < LIBUSB_DT_BOS_SIZE) {
        usbi_err(ctx, "invalid bos bLength (%d)", bos_header.bLength);
        return LIBUSB_ERROR_IO;
    }
    if (bos_header.bLength > size) {
        usbi_err(ctx, "short bos descriptor read %d/%d",
             size, bos_header.bLength);
        return LIBUSB_ERROR_IO;
    }

    _bos = calloc (1,
        sizeof(*_bos) + bos_header.bNumDeviceCaps * sizeof(void *));
    if (!_bos)
        return LIBUSB_ERROR_NO_MEM;

    usbi_parse_descriptor(buffer, "bbwb", _bos, host_endian);
    buffer += bos_header.bLength;
    size -= bos_header.bLength;

    /* Get the device capability descriptors */
    for (i = 0; i < bos_header.bNumDeviceCaps; i++) {
        if (size < LIBUSB_DT_DEVICE_CAPABILITY_SIZE) {
            usbi_warn(ctx, "short dev-cap descriptor read %d/%d",
                  size, LIBUSB_DT_DEVICE_CAPABILITY_SIZE);
            break;
        }
        usbi_parse_descriptor(buffer, "bbb", &dev_cap, host_endian);
        if (dev_cap.bDescriptorType != LIBUSB_DT_DEVICE_CAPABILITY) {
            usbi_warn(ctx, "unexpected descriptor %x (expected %x)",
                  dev_cap.bDescriptorType, LIBUSB_DT_DEVICE_CAPABILITY);
            break;
        }
        if (dev_cap.bLength < LIBUSB_DT_DEVICE_CAPABILITY_SIZE) {
            usbi_err(ctx, "invalid dev-cap bLength (%d)",
                 dev_cap.bLength);
            libusb_free_bos_descriptor(_bos);
            return LIBUSB_ERROR_IO;
        }
        if (dev_cap.bLength > size) {
            usbi_warn(ctx, "short dev-cap descriptor read %d/%d",
                  size, dev_cap.bLength);
            break;
        }

        _bos->dev_capability[i] = malloc(dev_cap.bLength);
        if (!_bos->dev_capability[i]) {
            libusb_free_bos_descriptor(_bos);
            return LIBUSB_ERROR_NO_MEM;
        }
        memcpy(_bos->dev_capability[i], buffer, dev_cap.bLength);
        buffer += dev_cap.bLength;
        size -= dev_cap.bLength;
    }
    _bos->bNumDeviceCaps = (uint8_t)i;
    *bos = _bos;

    return LIBUSB_SUCCESS;
}

/** \ingroup desc
 * Get a Binary Object Store (BOS) descriptor
 * This is a BLOCKING function, which will send requests to the device.
 *
 * \param handle the handle of an open libusb device
 * \param bos output location for the BOS descriptor. Only valid if 0 was returned.
 * Must be freed with \ref libusb_free_bos_descriptor() after use.
 * \returns 0 on success
 * \returns LIBUSB_ERROR_NOT_FOUND if the device doesn't have a BOS descriptor
 * \returns another LIBUSB_ERROR code on error
 */
int API_EXPORTED libusb_get_bos_descriptor(libusb_device_handle *handle,
    struct libusb_bos_descriptor **bos)
{
    struct libusb_bos_descriptor _bos;
    uint8_t bos_header[LIBUSB_DT_BOS_SIZE] = {0};
    unsigned char *bos_data = NULL;
    const int host_endian = 0;
    int r;

    /* Read the BOS. This generates 2 requests on the bus,
     * one for the header, and one for the full BOS */
    r = libusb_get_descriptor(handle, LIBUSB_DT_BOS, 0, bos_header,
                  LIBUSB_DT_BOS_SIZE);
    if (r < 0) {
        if (r != LIBUSB_ERROR_PIPE)
            usbi_err(handle->dev->ctx, "failed to read BOS (%d)", r);
        return r;
    }
    if (r < LIBUSB_DT_BOS_SIZE) {
        usbi_err(handle->dev->ctx, "short BOS read %d/%d",
             r, LIBUSB_DT_BOS_SIZE);
        return LIBUSB_ERROR_IO;
    }

    usbi_parse_descriptor(bos_header, "bbwb", &_bos, host_endian);
    usbi_dbg("found BOS descriptor: size %d bytes, %d capabilities",
         _bos.wTotalLength, _bos.bNumDeviceCaps);
    bos_data = calloc(_bos.wTotalLength, 1);
    if (bos_data == NULL)
        return LIBUSB_ERROR_NO_MEM;

    r = libusb_get_descriptor(handle, LIBUSB_DT_BOS, 0, bos_data,
                  _bos.wTotalLength);
    if (r >= 0)
        r = parse_bos(handle->dev->ctx, bos, bos_data, r, host_endian);
    else
        usbi_err(handle->dev->ctx, "failed to read BOS (%d)", r);

    free(bos_data);
    return r;
}

/** \ingroup desc
 * Free a BOS descriptor obtained from libusb_get_bos_descriptor().
 * It is safe to call this function with a NULL bos parameter, in which
 * case the function simply returns.
 *
 * \param bos the BOS descriptor to free
 */
void API_EXPORTED libusb_free_bos_descriptor(struct libusb_bos_descriptor *bos)
{
    int i;

    if (!bos)
        return;

    for (i = 0; i < bos->bNumDeviceCaps; i++)
        free(bos->dev_capability[i]);
    free(bos);
}

/** \ingroup desc
 * Get an USB 2.0 Extension descriptor
 *
 * \param ctx the context to operate on, or NULL for the default context
 * \param dev_cap Device Capability descriptor with a bDevCapabilityType of
 * \ref libusb_capability_type::LIBUSB_BT_USB_2_0_EXTENSION
 * LIBUSB_BT_USB_2_0_EXTENSION
 * \param usb_2_0_extension output location for the USB 2.0 Extension
 * descriptor. Only valid if 0 was returned. Must be freed with
 * libusb_free_usb_2_0_extension_descriptor() after use.
 * \returns 0 on success
 * \returns a LIBUSB_ERROR code on error
 */
int API_EXPORTED libusb_get_usb_2_0_extension_descriptor(
    struct libusb_context *ctx,
    struct libusb_bos_dev_capability_descriptor *dev_cap,
    struct libusb_usb_2_0_extension_descriptor **usb_2_0_extension)
{
    struct libusb_usb_2_0_extension_descriptor *_usb_2_0_extension;
    const int host_endian = 0;

    if (dev_cap->bDevCapabilityType != LIBUSB_BT_USB_2_0_EXTENSION) {
        usbi_err(ctx, "unexpected bDevCapabilityType %x (expected %x)",
             dev_cap->bDevCapabilityType,
             LIBUSB_BT_USB_2_0_EXTENSION);
        return LIBUSB_ERROR_INVALID_PARAM;
    }
    if (dev_cap->bLength < LIBUSB_BT_USB_2_0_EXTENSION_SIZE) {
        usbi_err(ctx, "short dev-cap descriptor read %d/%d",
             dev_cap->bLength, LIBUSB_BT_USB_2_0_EXTENSION_SIZE);
        return LIBUSB_ERROR_IO;
    }

    _usb_2_0_extension = malloc(sizeof(*_usb_2_0_extension));
    if (!_usb_2_0_extension)
        return LIBUSB_ERROR_NO_MEM;

    usbi_parse_descriptor((unsigned char *)dev_cap, "bbbd",
                  _usb_2_0_extension, host_endian);

    *usb_2_0_extension = _usb_2_0_extension;
    return LIBUSB_SUCCESS;
}

/** \ingroup desc
 * Free a USB 2.0 Extension descriptor obtained from
 * libusb_get_usb_2_0_extension_descriptor().
 * It is safe to call this function with a NULL usb_2_0_extension parameter,
 * in which case the function simply returns.
 *
 * \param usb_2_0_extension the USB 2.0 Extension descriptor to free
 */
void API_EXPORTED libusb_free_usb_2_0_extension_descriptor(
    struct libusb_usb_2_0_extension_descriptor *usb_2_0_extension)
{
    free(usb_2_0_extension);
}

/** \ingroup desc
 * Get a SuperSpeed USB Device Capability descriptor
 *
 * \param ctx the context to operate on, or NULL for the default context
 * \param dev_cap Device Capability descriptor with a bDevCapabilityType of
 * \ref libusb_capability_type::LIBUSB_BT_SS_USB_DEVICE_CAPABILITY
 * LIBUSB_BT_SS_USB_DEVICE_CAPABILITY
 * \param ss_usb_device_cap output location for the SuperSpeed USB Device
 * Capability descriptor. Only valid if 0 was returned. Must be freed with
 * libusb_free_ss_usb_device_capability_descriptor() after use.
 * \returns 0 on success
 * \returns a LIBUSB_ERROR code on error
 */
int API_EXPORTED libusb_get_ss_usb_device_capability_descriptor(
    struct libusb_context *ctx,
    struct libusb_bos_dev_capability_descriptor *dev_cap,
    struct libusb_ss_usb_device_capability_descriptor **ss_usb_device_cap)
{
    struct libusb_ss_usb_device_capability_descriptor *_ss_usb_device_cap;
    const int host_endian = 0;

    if (dev_cap->bDevCapabilityType != LIBUSB_BT_SS_USB_DEVICE_CAPABILITY) {
        usbi_err(ctx, "unexpected bDevCapabilityType %x (expected %x)",
             dev_cap->bDevCapabilityType,
             LIBUSB_BT_SS_USB_DEVICE_CAPABILITY);
        return LIBUSB_ERROR_INVALID_PARAM;
    }
    if (dev_cap->bLength < LIBUSB_BT_SS_USB_DEVICE_CAPABILITY_SIZE) {
        usbi_err(ctx, "short dev-cap descriptor read %d/%d",
             dev_cap->bLength, LIBUSB_BT_SS_USB_DEVICE_CAPABILITY_SIZE);
        return LIBUSB_ERROR_IO;
    }

    _ss_usb_device_cap = malloc(sizeof(*_ss_usb_device_cap));
    if (!_ss_usb_device_cap)
        return LIBUSB_ERROR_NO_MEM;

    usbi_parse_descriptor((unsigned char *)dev_cap, "bbbbwbbw",
                  _ss_usb_device_cap, host_endian);

    *ss_usb_device_cap = _ss_usb_device_cap;
    return LIBUSB_SUCCESS;
}

/** \ingroup desc
 * Free a SuperSpeed USB Device Capability descriptor obtained from
 * libusb_get_ss_usb_device_capability_descriptor().
 * It is safe to call this function with a NULL ss_usb_device_cap
 * parameter, in which case the function simply returns.
 *
 * \param ss_usb_device_cap the USB 2.0 Extension descriptor to free
 */
void API_EXPORTED libusb_free_ss_usb_device_capability_descriptor(
    struct libusb_ss_usb_device_capability_descriptor *ss_usb_device_cap)
{
    free(ss_usb_device_cap);
}

/** \ingroup desc
 * Get a Container ID descriptor
 *
 * \param ctx the context to operate on, or NULL for the default context
 * \param dev_cap Device Capability descriptor with a bDevCapabilityType of
 * \ref libusb_capability_type::LIBUSB_BT_CONTAINER_ID
 * LIBUSB_BT_CONTAINER_ID
 * \param container_id output location for the Container ID descriptor.
 * Only valid if 0 was returned. Must be freed with
 * libusb_free_container_id_descriptor() after use.
 * \returns 0 on success
 * \returns a LIBUSB_ERROR code on error
 */
int API_EXPORTED libusb_get_container_id_descriptor(struct libusb_context *ctx,
    struct libusb_bos_dev_capability_descriptor *dev_cap,
    struct libusb_container_id_descriptor **container_id)
{
    struct libusb_container_id_descriptor *_container_id;
    const int host_endian = 0;

    if (dev_cap->bDevCapabilityType != LIBUSB_BT_CONTAINER_ID) {
        usbi_err(ctx, "unexpected bDevCapabilityType %x (expected %x)",
             dev_cap->bDevCapabilityType,
             LIBUSB_BT_CONTAINER_ID);
        return LIBUSB_ERROR_INVALID_PARAM;
    }
    if (dev_cap->bLength < LIBUSB_BT_CONTAINER_ID_SIZE) {
        usbi_err(ctx, "short dev-cap descriptor read %d/%d",
             dev_cap->bLength, LIBUSB_BT_CONTAINER_ID_SIZE);
        return LIBUSB_ERROR_IO;
    }

    _container_id = malloc(sizeof(*_container_id));
    if (!_container_id)
        return LIBUSB_ERROR_NO_MEM;

    usbi_parse_descriptor((unsigned char *)dev_cap, "bbbbu",
                  _container_id, host_endian);

    *container_id = _container_id;
    return LIBUSB_SUCCESS;
}

/** \ingroup desc
 * Free a Container ID descriptor obtained from
 * libusb_get_container_id_descriptor().
 * It is safe to call this function with a NULL container_id parameter,
 * in which case the function simply returns.
 *
 * \param container_id the USB 2.0 Extension descriptor to free
 */
void API_EXPORTED libusb_free_container_id_descriptor(
    struct libusb_container_id_descriptor *container_id)
{
    free(container_id);
}

/** \ingroup desc
 * Retrieve a string descriptor in C style ASCII.
 *
 * Wrapper around libusb_get_string_descriptor(). Uses the first language
 * supported by the device.
 *
 * \param dev a device handle
 * \param desc_index the index of the descriptor to retrieve
 * \param data output buffer for ASCII string descriptor
 * \param length size of data buffer
 * \returns number of bytes returned in data, or LIBUSB_ERROR code on failure
 */
int API_EXPORTED libusb_get_string_descriptor_ascii(libusb_device_handle *dev,
    uint8_t desc_index, unsigned char *data, int length)
{
    unsigned char tbuf[255]; /* Some devices choke on size > 255 */
    int r, si, di;
    uint16_t langid;

    /* Asking for the zero'th index is special - it returns a string
     * descriptor that contains all the language IDs supported by the
     * device. Typically there aren't many - often only one. Language
     * IDs are 16 bit numbers, and they start at the third byte in the
     * descriptor. There's also no point in trying to read descriptor 0
     * with this function. See USB 2.0 specification section 9.6.7 for
     * more information.
     */

    if (desc_index == 0)
        return LIBUSB_ERROR_INVALID_PARAM;

    r = libusb_get_string_descriptor(dev, 0, 0, tbuf, sizeof(tbuf));
    if (r < 0)
        return r;

    if (r < 4)
        return LIBUSB_ERROR_IO;

    langid = tbuf[2] | (tbuf[3] << 8);

    r = libusb_get_string_descriptor(dev, desc_index, langid, tbuf,
        sizeof(tbuf));
    if (r < 0)
        return r;

    if (tbuf[1] != LIBUSB_DT_STRING)
        return LIBUSB_ERROR_IO;

    if (tbuf[0] > r)
        return LIBUSB_ERROR_IO;

    for (di = 0, si = 2; si < tbuf[0]; si += 2) {
        if (di >= (length - 1))
            break;

        if ((tbuf[si] & 0x80) || (tbuf[si + 1])) /* non-ASCII */
            data[di++] = '?';
        else
            data[di++] = tbuf[si];
    }

    data[di] = 0;
    return di;
}

